The invention relates to a method and a device for controlling a motor vehicle comprising an electrohydraulic brake system with driving dynamics control, a master brake cylinder operable by means of a brake pedal, at least one pressure fluid supply device which can be actuated by an electronic control unit and the pressure of which can be applied to wheel brakes of the vehicle which are connectable to the master brake cylinder, on the other hand, by way of at least one hydraulic connection that is closable by means of a separating valve, each one inlet valve and one outlet valve connected upstream of the wheel brakes, as well as with a device for detecting brake application which comprises a magnet as a signal transmitter and a sensor element.
In principally known driving dynamics control systems, a driving dynamics control action regularly causes automatic interruption of a hydraulic connection between master cylinder and wheel brakes which is normally constantly opened, with the result that one or both of the pistons of the master cylinder in braking maneuvers during the driving dynamics control action (ESP control intervention) or during an ABS intervention is quasi undisplaceable in relation to the housing due to the separating valves being closed. One cause is that pressure fluid cannot be conducted in the direction of the wheel brakes. The ESP intervention takes place irrespective of the driver, and the rudimentary piston travel is not sufficient to indicate a change of travel. Also, the ESP action cannot be interrupted by the driver so that only limited deceleration is possible. Further, an actuating signal cannot be generated, and e.g. stop light signaling is impossible. The traffic in the rear is informed about the braking request of the driver only after the driving dynamics control action is completed.
Another special objective is to avoid accidents and reduce the consequences of an accident. To this end, passive and active safety systems are cross-linked to each other in order to achieve data exchange among the safety systems and thus provide information about the vehicle's condition, the vehicle ambience and the driver himself.
In view of the above, the objective is to offer a method and a device which is simple in terms of its structure to solve the problems, i.e. to enable reliable monitoring of a piston also during a driving dynamics control action, and to detect the driver's request during the entire actuating travel in order to optimize control operations of the vehicle by detecting the driver's request.